Three-dimensional quantitative structure-activity relationship analyses of beta-lactam antibiotics and tripeptides as substrates of the mammalian H+/peptide cotransporter PEPT1.
Level 5 - mechanism / opinion, no new human data
In vitro cell culture binding assays and in silico QSAR computational modeling.
PubMed 15974593 · doi:10.1021/jm048982w
What was done
Researchers performed three-dimensional quantitative structure-activity relationship (3D-QSAR) studies using the comparative molecular similarity indices analysis (CoMSIA) method on a training set of 98 compounds. Affinity constants of beta-lactam antibiotics and tripeptides were determined experimentally in Caco-2 cells expressing the PEPT1 transporter. Field contribution maps were used to identify key interaction regions, and the resulting model was applied to design a novel druglike dipeptide mimetic.
What was found
The 3D-QSAR CoMSIA model achieved a cross-validated coefficient q(2) of 0.828 and a correlation coefficient r(2) of 0.937. The predicted K(i) value for the newly designed compound was confirmed experimentally. Specific numerical affinity constants and K(i) values were not detailed in the abstract.
Why it matters
Clarifying the structural determinants of PEPT1 binding aids the rational design of orally bioavailable peptidomimetic drugs and prodrugs targeted to the intestinal peptide transporter.
Limits
The study is restricted to computational analysis and in vitro Caco-2 cell assays, lacking in vivo pharmacokinetic and bioavailability testing in animals or humans. Numerical binding constants and chemical identities of the tested compounds were not reported in the abstract.
Cited by
- supports Di- and tripeptides can be orally bioavailable if they have the appropriate conformation and size.